How can I prevent my clothes dryer door from fogging up?

Question

When I turn the air conditioning on in my house, the inside of the window in the clothes dryer door fogs up. Also, if clothes are left in the dryer, they become slightly damp again. How can I prevent this?

The dryer vent consists of:

• ~9 ft. of 4" rigid pipe.
  
• One 90° elbow.
  
• 2 ft. length of Semi-Rigid duct.
  
• One louvered vent hood.
  

^{All seams are sealed using foil tape}

Answer 1

I went through this recently with my girlfriends dryer. Here is what I learned:

1. Her outside vent hood seeped rainwater, not much but enough
2. Her ductwork had a tiny amount of lint which soaked up the rainwater
3. Her “outside air” ducting for the all-electric central heat and air system damper didn’t open all the way causing the air to be drawn from and through the dryer ducting. The moisture in the ductwork lint was drawn into the clothing left in the dryer. (Her house is new and sealed very tightly!)

An additional clue something wasn’t right was indicated by the exterior vent for her kitchen cook stove - it “rattled” when the air conditioner ran!

Solution:

1. Replaced the dryer ductwork and exterior vent.
2. Disassembled dryer and cleaned entire dryer ductwork path
3. Cleaned the central air exterior air feeder pipe, cleaned the exterior dampener
4. Replaced furnace filter.
5. Cleaned a/c condensate pipe (ran hose water through it until it was no longer draining “green” water)
6. Fixed her supper on the Weber charcoal grill.

She is happy now. The dryer no longer “stinks” from the “wet lint” smell, her clothes remain dry and her air conditioner is working better.

Answer 2

My guess is that you need to improve the seal on the thru the wall vent. The air-conditioning is cooling the house along with the objects in it. The humid air is entering the dryer via the louvered outlet. The air cools as it makes contact with the colder surfaces of the dryer resulting in condensation. You may be able to improve the seal on the louvers by removing any built up lint. Installation of a backdraft damper will also help.